Add support for tracing fork children

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 56 insertions, 0 deletions

diff --git a/util.c b/util.c
new file mode 100644
index 0000000..76a8a36
--- /dev/null
+++ b/util.c
@@ -0,0 +1,56 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+static FILE *trace_fp;
+static char last_char = '\n';
+static pid_t last_pid = 0;
+
+
+void
+set_trace_output(FILE *fp)
+{
+	trace_fp = fp;
+}
+
+
+void
+tprintf(struct process *proc, const char *fmt, ...)
+{
+	va_list ap;
+	if (fmt[0] == '\n' && fmt[1]) {
+		last_pid = 0;
+		fmt = &fmt[1];
+	}
+	if (last_char == '\n')
+		fprintf(trace_fp, "[%ju] ", (uintmax_t)proc->pid);
+	else if (proc->pid != last_pid)
+		fprintf(trace_fp, "\n[%ju] ", (uintmax_t)proc->pid);
+	va_start(ap, fmt);
+	vfprintf(trace_fp, fmt, ap);
+	last_pid = proc->pid;
+	last_char = strchr(fmt, '\0')[-1];
+	va_end(ap);
+}
+
+
+_Noreturn void
+eprintf(const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	fprintf(stderr, "%s%s: ", last_char == '\n' ? "" : "\n", argv0);
+	vfprintf(stderr, fmt, ap);
+	switch (strchr(fmt, '\0')[-1]) {
+	case ':':
+		fprintf(stderr, " %s\n", strerror(errno));
+		break;
+	case '\n':
+		break;
+	default:
+		fprintf(stderr, "\n");
+		break;
+	}
+	va_end(ap);
+	exit(1);
+}